(1) Field of the Invention
The present invention generally relates to an engine mount, and more particularly to an engine mount for supporting an engine on a frame of an engine compartment of an automotive vehicle.
(2) Description of the Related Art
An engine mount for supporting an engine on an automotive vehicle, which includes a central axis, an outer cylinder and an inner member, is known. The inner member is provided within the outer cylinder along the central axis of the engine mount. For example, Japanese Laid-Open Patent Application No. 4-321833 discloses such an engine mount.
The engine mount of the above publication includes an outer cylinder fixed to a frame of an automotive vehicle by using a bracket, and an inner member to which an engine is fixed by using a mounting bolt. The outer cylinder and the inner member are interconnected by an elastic member such that relative positions of the outer cylinder and the inner member in both an axial direction and a radial direction of the engine mount are changeable.
In the engine mount of the above publication, when the vehicle is running, vibrations from the engine are transferred to the engine mount via the bracket. Such vibrations are mostly absorbed by changes in length of the elastic member interconnecting the outer cylinder and the inner member. There are few vibrations transferred from the engine to the vehicle via the engine mount.
The engine mount of the above publication includes a stopper of an elastic material which is provided on both the outer cylinder and the inner member. The stopper is in contact with the outer cylinder and the inner member so as to prevent a change in length of one of the outer cylinder and the inner member relative to the other from increasing beyond a reference level. Therefore, when the vehicle is running, it is possible for the engine mount of the above publication to maintain the engine in the vehicle in a stable, suitable condition.
Generally, the engine mount is fixed to the frame of the engine compartment of the vehicle after related parts, such as brackets and stays, are attached to the engine mount. After the engine mount is fixed to the frame of the engine compartment, the engine is mounted in the vehicle through the engine mount. As described above, the engine is fixed to the inner member by using the mounting bolt, and the bracket is fixed to the frame of the engine compartment. In order to suitably carry out the mounting of the engine in the vehicle, it is desirable that the circumferential position of the bracket around the central axis of the inner member in the engine mount is a correct reference position after the engine mount is fixed to the frame of the engine compartment and before the engine is mounted on the vehicle.
The engine mount of the above publication includes the stopper which always exerts a pressing force on the outer cylinder and the inner member to prevent the change in length of one of the outer cylinder and the inner member relative to the other from increasing beyond the reference level. Since the outer cylinder is pressed by the stopper due to an elastic force of the stopper, a frictional force between the stopper and the outer cylinder is produced. If the circumferential positions of the outer cylinder and the bracket relative to each other around the central axis of the engine mount are correctly the reference positions, the frictional force serves to prevent the circumferential positions of the bracket and the outer cylinder from changing with respect to each other.
During the fixing of the engine mount to the frame of the engine compartment, a relatively great torque may be exerted on the outer cylinder or the bracket. In the case of the engine mount of the above publication, if such torque is exerted on the outer cylinder or the bracket, the circumferential positions of the outer cylinder and the bracket around the central axis of the engine mount may deviate from the reference positions.
Since the deviated positions of the outer cylinder and the bracket are maintained by the frictional force between the stopper and the outer cylinder in the engine mount of the above publication, it is difficult to correct the deviated positions of the outer cylinder and the bracket, after the engine mount is fixed to the frame of the engine compartment, without using a special jig or performing a complicated operation.
Further, if the deviated positions of the outer cylinder and the bracket are maintained, it is impossible to suitably carry out the mounting of the engine in the vehicle through the engine mount. In the assembly line, it cannot be determined whether the circumferential positions of the outer cylinder and the bracket around the central axis of the engine mount are correctly aligned at the reference positions unless it is found that the engine is suitably fixed to the engine mount.
Therefore, in the case of the engine mount of the above publication, when it is found that the engine is not suitably fixed to the engine mount, it is necessary to stop the mounting of the engine in the vehicle through the engine mount, and the deviated positions of the outer cylinder and the bracket must be corrected to the reference positions by using a special jig or performing a complicated operation.